Guidewires having a vapor deposited primer coat

ABSTRACT

An intraluminal device having an adhesive primer coat formed of a carbonaceous material and a lubricious top coat of a hydrophilic polymeric material. The invention also comprises the methods of making such intraluminal devices. The primer coat of the invention may comprise pure carbon, or a carbon based material such as a polymer. Preferably, the primer coat has a thickness of about 0.1 to about 2 μm. In a presently preferred embodiment, the primer coat is applied using chemical vapor deposition (CVD), but in certain embodiments, physical vapor deposition (PVD) may be suitable. The deposited primer coat forms an effective substrate for adhesion of the hydrophilic polymer top coat.

CROSS REFERENCE TO RELATED APPLICATIONS

This is a continuation application of co-pending divisional applicationhaving U.S. Ser. No. 09/772,803 filed Jan. 29, 2001, which is adivisional application of U.S. Ser. No. 09/092,229 filed Jun. 5, 1998,now U.S. Pat. No. 6,203,505, the contents of which are herebyincorporated by reference.

BACKGROUND OF THE INVENTION

This invention is directed to the field of elongated intraluminaldevices having lubricious coatings, and, in particular, to a guidewirehaving a thin carbonaceous primer coat and a hydrophilic polymer topcoat.

In a typical coronary procedure a guiding catheter having a preformeddistal tip is percutaneously introduced into a patient's peripheralartery, e.g. femoral or brachial artery, by means of a conventionalSeldinger technique and advanced therein until the distal tip of theguiding catheter is seated in the ostium of a desired coronary artery.There are two basic techniques for advancing a guidewire into thedesired location within the patient's coronary anatomy, the first is apreload technique which is used primarily for over-the-wire (OTW)devices and the bare wire technique which is used primarily for railtype systems. With the preload technique, a guidewire is positionedwithin an inner lumen of an OTW device such as a dilatation catheter orstent delivery catheter with the distal tip of the guidewire justproximal to the distal tip of the catheter and then both are advancedthrough the guiding catheter to the distal end thereof. The guidewire isfirst advanced out of the distal end of the guiding catheter into thepatient's coronary vasculature until the distal end of the guidewirecrosses the arterial location where the interventional procedure is tobe performed, e.g. a lesion to be dilated or a dilated region where astent is to be deployed. The catheter, which is slidably mounted ontothe guidewire, is advanced out of the guiding catheter into thepatient's coronary anatomy over the previously introduced guidewireuntil the operative portion of the intravascular device, e.g. theballoon of a dilatation or a stent delivery catheter, is properlypositioned across the arterial location. Once the catheter is inposition with the operative means located within the desired arteriallocation, the interventional procedure is performed. The catheter canthen be removed from the patient over the guidewire. Usually, theguidewire is left in place for a period of time after the procedure iscompleted to ensure reaccess to the arterial location if it isnecessary. For example, in the event of arterial blockage due todissected lining collapse, a rapid exchange type perfusion ballooncatheter such as described and claimed in U.S. Pat. No. 5,516,336(McInnes et al.), can be advanced over the in-place guidewire so thatthe balloon can be inflated to open up the arterial passageway and allowblood to perfuse through the distal section of the catheter to a distallocation until the dissection is reattached to the arterial wall bynatural healing.

With the bare wire technique, the guidewire is first advanced by itselfthrough the guiding catheter until the distal tip of the guidewireextends beyond the arterial location where the procedure is to beperformed. Then a rail type catheter, such as described in U.S. Pat. No.5,061,395 (Yock). and the previously discussed McInnes et al. which areincorporated herein by reference, is mounted onto the proximal portionof the guidewire which extends out of the proximal end of the guidincatheter which is outside of the patient. The catheter is advanced overthe catheter, while the position of the guidewire is fixed, until theoperative means on the rail type catheter is disposed within thearterial location where the procedure is to be performed. After theprocedure the intravascular device may be withdrawn from the patientover the guidewire or the guidewire advanced further within the coronaryanatomy for an additional procedure.

Conventional guidewires for angioplasty, stent delivery, atherectomy andother vascular procedures usually comprise an elongated core member withone or more tapered sections near the distal end thereof and a flexiblebody such as a helical coil or a tubular body of polymeric materialdisposed about the distal portion of the core member. A shapeablemember, which may be the distal extremity of the core member or aseparate shaping ribbon which is secured to the distal extremity of thecore member extends through the flexible body and is secured to thedistal end of the flexible body by soldering, brazing or welding whichforms a rounded distal tip. Torquing means are provided on the proximalend of the core member to rotate, and thereby steer, the guidewire whileit is being advanced through a patient's vascular system.

Further details of guidewires, and devices associated therewith forvarious interventional procedures can be found in U.S. Pat. No.4,748,986 (Morrison et al.); U.S. Pat. No. 4,538,622. (Samson et al.):U.S. Pat. No. 5,135,503 (Abrams); U.S. Pat. No. 5,341,818 (Abrams etal.); and U.S. Pat. No. 5,345,945 (Hodgson et al.) which are herebyincorporated herein in their entirety by reference thereto.

Guidewires have been the subject of continual improvement.

One direction of improvement has centered on reducing the surfacefriction of the guidewire to facilitate relative movement between theguidewire and a guiding catheter or a dilatation catheter within apatient's body lumen. Much of the innovation has centered on laminatinglow friction, polymeric materials onto the surface of the guidewire.However, it has proven difficult to obtain a tenacious bond between thelubricious polymer coating and the material of the guidewire. Further,achieving a uniform coat of polymer over the helical shapeable distaltip of most guidewires presents several difficulties. For example,bridging of the coat material between adjacent coils interferes with thedesigned flexibility of the distal tip and thereby effects performanceof the guidewire.

In addition to guidewires, many intraluminal devices can benefit from alubricious surface to facilitate insertion and guidance to the desiredintraluminal destination. Reducing friction also minimizes luminaltrauma caused by insertion of these devices, particularly in bloodvessels such as coronary arteries. As with guidewires, much has beendone with the prior art lubricious polymeric coatings to produceintraluminal devices having low friction surfaces. However, a number ofdrawbacks are associated with the use of polymeric coatings. Providingsuch devices with a uniform and tenacious coating is technicallydifficult and correspondingly expensive.

There remains a need for intraluminal devices having a lubriciouspolymeric coating which is thin and which is strongly adhered to thedevice. Further, there is a need for a process of applying suchlubricious polymeric coatings in a repeatable, uniform and costeffective manner. This invention satisfies these and other needs.

SUMMARY OF THE INVENTION

This invention comprises an intraluminal device having a vapor depositedprimer coat formed of a carbonaceous material and a lubricious top coatof a hydrophilic polymeric material. The invention also comprises themethods of making such intraluminal devices.

The vapor deposited primer coat of the invention may comprisesubstantially pure carbon, or a carbon-based material such as plasmapolymerized hydrocarbons, polyurethane, or nylon, and preferably has athickness of about 0.1 to about 2 μm. A variety of carbonaceous sourcematerials may be used to form the primer coat depending on thecomposition of the primer coat and the coating method used.. The primercoat is applied to the surface of the intraluminal device using chemicalvapor deposition (CVD), or in certain embodiments as discussed below,physical vapor deposition (PVD). The deposited primer coat forms aneffective substrate for adhesion of a later applied hydrophilic polymertop coat. The hydrophilic polymer top coat may be applied by a varietyof methods, including CVD, PVD, dipping, spraying and the like.

In a presently preferred embodiment of the invention, the primer coatand the hydrophilic top coat are applied to the surface of a distal tipcoil of a guidewire. The use of vapor deposition provides a thin primercoat which provides uniform coverage of the helical coil. In a presentlypreferred embodiment of the invention, at least a stretched section ofthe coil are coated such that the adjacent turns of the coated coils donot touch one another. A thicker, less uniform primer coat would likelybridge the adjacent coils, or significantly increase the diameter of thecoils so that bridging would likely result in the lubricious top coat,which can interfere with guidewire performance.

The deposited primer coat of the invention has superior adhesion to thebase material of an intraluminal device, and provides improved adhesionbetween a hydrophilic top coat and the device. Additionally, thedeposited primer coat does not bridge the adjacent turns of guidewiretip coils, and does not significantly increase the thickness of thecoating on the device. These and other advantages of the invention willbecome more apparent from the following detailed description andaccompanying exemplary drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates guidewire of the invention with a shapeable coil tipand a distal portion having an adhesive primer coat and a hydrophilicpolymer top coat.

FIG. 2 is a cross section of the intermediate coil of the guidewire ofFIG. 1.

FIG. 3 is a sectional detail of the shapeable coil showing thehydrophilic polymer top coat.

FIG. 4 is a further detail of FIG. 3, showing the hydrophilic polymertop coat and the adhesive primer coat.

FIG. 5 is schematic diagram of a CVD apparatus suitable for the practiceof this invention.

DETAILED DESCRIPTION OF THE INVENTION

FIGS. 1-4 illustrate a guidewire 10 having features of this inventionthat generally include an elongated core member 12 and a distal tip 14having a thin carbonaceous primer coat and a hydrophilic top coat on atleast a portion thereof. The distal tip 14, which may be shaped orshapeable, comprises a flexible helical coil 16 and a rounded member 18on the distal extremity, preferably formed by a solder plug securinghelical coil 16 to core member 12. FIG. 3 shows a detail of the distalportion 20 of the helical coil 16 which has a uniform hydrophilicpolymer coating 22. Various portions of the guidewire may be coated asdesired. In a presently preferred embodiment, the distal 30 cm ofguidewire 10 is coated, which includes the flexible helical coil 16 anda portion of the core member proximal to the intermediate coils. Inother embodiments, only the coils 16 or only a distal portion of thecoils, such as the distal 3 cm coils, may be coated, depending on thedesired guidewire characteristics.

FIG. 4 is a further sectional detail of helical coil 16, showing thebase material 24 of the coil, adhesive primer coat 26 and hydrophilicpolymer top coat 22. Generally, base material 24 of guidewire 10 isstainless steel, but it may comprise a shape memory material such asnickel-titanium alloys or other materials. Primer coat 26 is eithersubstantially pure carbon, or a carbon-based material.

In the embodiment in which the primer coat 26 is substantially purecarbon, a variety of source materials may be used to form the carbonprimer coat, including graphite and pyrolytic carbon. The presentlypreferred coating method for applying a substantially pure carbon primercoating 26 from a graphite or pyrolytic carbon source is physicalvapor-deposition.

The presently preferred coating method for applying a carbon-basedprimer coating 26 is chemical vapor deposition. It should be understoodthat the carbon-based primer coating 26 applied by CVD comprises aplasma polymerized coating, so that the resulting polymer comprises anamorphous structure having groups in the structure other than themonomer groups of the source materials. For example, plasma polymerizedpolyethylene may include a variety of functional groups, such as vinyl,in addition to the methylene groups. The presently preferredcarbon-based primer coating 26 is plasma polymerized nylon or plasmapolymerized polyethylene. However, a variety of suitable carbon-basedpolymeric primer coatings may be used including plasma polymerizedpolypropylene, plasma polymerized polyurethane, and the like. A varietyof suitable carbon based source materials may be used to form thecarbon-based primer coating 26. For example, vapor reactants having thecarbonyl and amine functional groups characteristic of nylon, such asadipic acid and hexanediamine, may be used to form a plasma polymerizednylon primer coat. Additionally, hydrocarbons such as methane, ethane,hexane and the like, may be used as source materials. Primer coat 26 isvery thin, generally about 0.1 to about 2 μm depending on the type ofmaterial.

Any suitable hydrophilic polymer may be used as top coat 22, includingpoly(N-vinylpyrrolidone) (PVP), polyethylene oxide (PEO), Hydro Gel™,methacrylates and the like. Generally, the thickness of top coat 22 isabout 0.0025 mm (0.1 mil) to about 0.015 mm (0.5 mil), but may varydepending on the application. Any suitable means of applying top coat 22may be employed, including vapor deposition, dipping, spraying and thelike.

The length of the guidewire 10 may be about 160 cm to about 310 cm. TheOD of the guidewire and distal tip coil is about 0.025 cm to about 0.05cm. The distal tip coil is formed from wire having a diameter of about0.002 in (0.05 mm) to about 0.0055 in (0.14 mm). The spacing betweenadjacent turns of the helically wound coils varies along the length ofthe device, from substantially stacked coils having substantially spacebetween adjacent coils, to stretched coils having a spacing of about 15%to about 30% of the wire diameter.

CVD typically involves vaporized compounds flowing over a substrate. Aplasma can be generated via RF energy or the like to activate thedeposition reactions. The reaction of the compounds in the plasma, stateand at the substrate surface results in a film coating. CVD should beperformed at low pressures to enhance the quality of the coating. Theuse of a CVD process allows the application of very thin, uniform andrepeatable primer coats, without causing bridging between adjacent coilson the guidewire.

FIG. 5 is a schematic diagram of a suitable CVD apparatus 28, having areaction chamber 30, gas/vapor source 31, gas/vapor inlet 32, anelectronic pressure regulator system 33, a pressure sensor, 34, a vacuumpump 35, a RF power supply and regulator 36, and RF induction coils 37around the outside of the chamber. As an alternative to induction coils,plasma can be generated via capacitor plates (not shown), typicallylocated inside the chamber 30. Before deposition of the primer coat 26,the guidewire is typically cleaned using well known procedures, such aswashing with a solvent such as 1,1,1, trichloroethane, or exposure toultrasonication or the plasma gas in the CVD chamber. Generally, theguidewire is suitably masked and placed in reaction chamber 30. Anonreactive gas such as argon is used to purge the chamber atmosphereand the pressure is reduced to less than about 50 mtorr. RF power supply36 and induction coils 37 are used to generate a plasma from the chambergas. Desired gases or vapors are introduced through inlets 32, which inthe presence of the plasma, polymerize and deposit on the substrate. Thereaction is allowed to continue until a sufficiently thick layer ofprimer coat is deposited, then the plasma is turned off and the chamberpurged again with nonreactive gas. In general, the plasma power is about5 to 50 Watts and the gas/vapor flow is less than about 20 sccm. Underthese parameters, a suitable primer coat is applied in about 1 to 10minutes. A plasma polymerized polyethylene coating was applied usinghexane vapor as a source material, at a power of 50W and a flow rate of5 sccm for 10 minutes.

The primer coat 26 may be applied using physical vapor deposition (PVD).In general, PVD involves generation of the coating, transport of thecoating to the substrate and growth of the coating on the substrate.Generation of the coating may be achieved either by evaporation orsputtering. In evaporative schemes, thermal energy from resistance,induction, electron-beam or laser beam sources is used to vaporize thecoating. Sputtering, on the other hand uses plasma ions generated bydirect current or radio frequency to energize and eject species of thecoating material towards the substrate. Generating species with greaterenergies can improve adhesion with the substrate. Transport of thevaporized coating generally depends on the partial pressure of thevaporized coating; for example molecular flow occurs at low partialpressures while viscous flow occurs at higher partial pressures.Depending on the technique, the substrate may also be biased. Finally,growth of the coating depends on the energy of the vaporized coating andsubstrate temperature. One of skill in the art will be able to tailorthe conditions to the type of coating being applied and the substratematerial.

While the invention has been described herein primarily with referenceto presently preferred embodiments comprising an adhesive primer coatapplied to a guidewire through vapor deposition, various modificationsand improvements can be made to the invention without departing from thescope thereof. For example, while the carbon-based primer coatings wereprimarily described as a CVD polymerized coating, PVD may also be usedto apply the primer coat. The coatings may be applied to a variety ofintraluminal products including electrophysiology devices, atherectomycatheters, stents and the like without departing from the scope thereof.

1-12. (canceled)
 13. An intraluminal stent having a primer coat formed of carbonaceous material and vapor deposited on at least a portion of the device such that the coated portion is unexposed to a blood flow.
 14. The intraluminal stent of claim 13, wherein the primer coat has a uniform thickness of not more than about 2 μm.
 15. The intraluminal stent of claim 13, wherein the primer coat is selected from the group consisting of carbon, plasma polymerized nylon, plasma polymerized polyurethane, plasma polymerized polyethylene, and plasma polymerized hydrocarbons.
 16. The intraluminal stent of claim 13, wherein the primer coat is vapor deposited on the entire device.
 17. A method of making an intraluminal stent having a lubricious surface, comprising: applying a primer coat formed of a carbonaceous material on at least a portion of the device by vapor deposition; and applying a hydrophilic polymeric coat on at least a portion of the primer coat.
 18. The method of claim 17, wherein the primer coat is applied until the primer coat is about 0.1 μm to about 2 μm thick.
 19. The method of claim 17, wherein the primer coat is applied by chemical vapor deposition.
 20. The method of claim 17, wherein the primer coat is applied by physical vapor deposition.
 21. The method of claim 17, wherein the carbonaceous primer coat is substantially pure carbon.
 22. The method of claim 21, wherein substantially pure carbon includes source materials such as graphite and pyrolytic carbon.
 23. The method of claim 21, wherein the substantially pure carbon primer coat is applied on at least a portion of the device by physical vapor deposition.
 24. The method of claim 17, wherein the primer coat is a carbon-based material.
 25. The method of claim 24, wherein the carbon-based primer coat is applied on at least a portion of the device by chemical vapor deposition.
 26. The method of claim 25, wherein the carbon-based primer coat comprises a plasma polymerized coat such that the resulting polymer coat includes an amorphous structure having groups in the structure other than monomer groups of the source materials.
 27. The method of claim 26, wherein the carbon-based primer coat is selected from the group consisting of plasma polymerized nylon, plasma polymerized polyethylene, plasma polymerized polypropylene, and plasma polymerized polyurethane.
 28. The method of claim 26, wherein the source materials of the carbon-based primer coat include adipic acid, hexanediamine, and hydrocarbons.
 29. The method of claim 17, wherein the hydrophilic polymer coat is selected from the group consisting of poly(N-vinylpyrrolidone), polyethylene oxide, and methacrylates.
 30. The method of claim 17, wherein the hydrophilic polymer coat is applied by vapor deposition.
 31. The method of claim 17, wherein the hydrophilic polymer coat is applied by dipping.
 32. The method of claim 17, wherein the hydrophilic polymer coat is applied by spraying.
 33. A method of making an intraluminal stent having a carbonaceous primer coat for facilitating the adhesion of a polymeric top coat, comprising: applying a primer coat formed of a carbonaceous material on at least a portion of the device by vapor deposition. 